A lot guys underestimate the importance of having a quality couch. Considering we spend so much time there, eating, watching TV, relaxing, etc. you want to have something nice. Also, having a well stocked bar is key. The serving cart you mention is a great idea, something you can easily tuck away in a corner, or place against a wall while entertaining. I always keep a bottle of white wine in the fridge for my female guests, and always have a clean bathroom for them. That means the sink, countertop, and toilet bowl are void of anything that shouldn’t be there. A fresh roll of toilet paper also gives a great impression.